Definition of a CD Writer

By Tiffany Garden

A CD writer is a common drive included on today's computers. It allows you to read and write CD-ROM disks, which is advantageous for keeping backups of your files, additional computer storage, and making music CDs. Many different companies make CD writers, but they work in the same way. They are also referred to as CD-R drives or CD burners.

Parts of a CD Writer

The main part of a CD writer is the laser. This consists of a laser lens, a tracking mechanism, and photodiodes. This is sometimes referred to as a drive head. The disk drive is where you put the disk in the drive, and it has a motor to spin it around. There are mirrors to focus the laser as well, and the photodiodes will process the information from reflected light.

How It Works

A CD writer is not very different from a standard CD-ROM drive. When you insert the disk, the varying light reflecting off the pits in the disk tell the sensors the type of information contained on the disk. The only difference with a CD writer is that you can insert special disks made with light-sensitive dye. The laser in the CD writer will calibrate to the specific frequency that will "burn" the information into the disk.

Types of Writable Disks

There are two different types of writable CDs made with two different types of dye: CD-R and CD-RW. CD-Rs can only be written onto once. CD-RWs are rewritable, which makes them handy for storing documents and computer backups. Some CD players and CD-ROM drives will have problems reading the CD-RWs because of the different dye, so music CDs are better off being burned to the CD-Rs.

Storage Capacity

A CD-R or CD-RW has the same amount of capacity physically. In reality, a CD-R has a bit more space, most of the 700 megabytes of the CD. CD-RWs need to be formatted if they are going to be written over several times. This cuts down on the total available space on the disk.

Burn Speed

There are many different speeds available for CD writers. The base speed of a CD-ROM drive was originally 156 kilobytes per second, and all drive speeds today use that number as a baseline. For example, a CD writer that is 56x speed means that it is 56 times faster than 156 kbps, making it capable of writing at 8,736 kilobytes per second. Burn quality can sometimes be an issue at the top speeds; manufacturers often solve this by including more powerful lasers in the CD writers.